The following documents and standards descriptions are hereby incorporated into the present disclosure as if fully set forth herein: 3GPP Technical Specification No. 36.300, version 10.3.0 (2011-03); 3GPP Technical Report No. 36.814, version 9.0.0 (2010-03); 3GPP Technical Specification No. 36.321, version 10.2.0 (2011-06); 3GPP Technical Specification No. 36.331, version 10.2.0 (2011-06); 3GPP Technical Specification No. 36.133, version 10.4.0 (2011-09); 3GPP Technical Specification No. 36.331, version 10.3.0 (2011-09); 3GPP Technical Specification No. 36.211, version 10.3.0 (2011-09); and 3GPP Technical Specification No. 36.213, version 10.3.0 (2011-09).
Standards have been proposed to modify existing downlink (DL) carriers in an effort to reduce an amount of bandwidth consumed by signaling overhead. The proposed standards may have a lack of available signals for an user equipment (UE) to achieve time and/or frequency lock with the modified carriers.
Accordingly, there is a need for a downlink reference signal for time and/or frequency tracking by a UE.